Every subsea telecommunications cable brings with it the issue of its maintenance and in particular, its repair on sustaining damage. Every cable is sooner or later liable to a break. If its owners are expecting further use from the cable, then it will need to be re-instated. This may seem painfully obvious yet it expresses some fundamental truths about all subsea cables: (1) how to ensure that the cable is resilient to damage in the first place; and (2) how the cable owner will respond when the cable sustains damage.
The Future for Cable Repair and Maintenance By Simon Frater
Much of the history of the telecommunications industry’s response to the risks to a cable on the seabed is better covered elsewhere. Suffice it to say that it has been driven from different directions. One is in response to the increasing extent and technological improvement of fishing techniques that permit deeper and more aggressive fishing tactics. Another is commercial pressure from the cable owner at system installation for the use of techniques that conceal the cable, given the loss of availability of ideal routes across the seabed that would have naturally provided better protection. The reduction of route availability has been caused by the use of the more ideal cable routes by earlier cables and the issue of recovering out-of-service cables so to free up previously used routes is outside the scope of this article. Increasing resilience to external threats to the cable has been achieved by progressive improvement to burial techniques. The development of seabed ploughing and post laid burial techniques has substantially improved resilience. Burial to 1 m has been commonplace for a substantial period, and demands for burial in excess of 3 m can no longer be considered exceptional. In some parts of the Asia-Pacific region it is commonplace. To achieve these depths, the assets available to implement them have also grown. Marine installers routinely hold seabed ploughs capable of achieving 3 m burial and remotely operated vehicles (“ROV’s”) with complementary capabilities. There are also a number of assets that are independently available in the marine engineering industry at large. The result is that it is probably true to say today that the cables installed in
the last 6 years have never been so well protected from external aggression. A further factor that is pertinent in the reduction of external damage to subsea telecommunications cables in some parts of the world, especially in the North Sea and the Western Approaches, is a significant reduction in fishing. If, and when, fish stocks recover sufficiently to permit extensive fishing once again, then an increase in incidence of external aggression to cables can be expected. No doubt this will test some of the improvements in protection introduced in the more recently installed cables. To a cable owner, a break on some part of its telecommunications network, especially a subsea segment, will at best cause it to lose margin resulting from switching the capacity that would have been carried on that segment to another cable very probably under some restoration agreement with a competitor. In the worst cases, a cable owner might suffer commercially irrecoverable losses of revenue, or actually having to pay more to carry its customers’ traffic than it will actually receive from them. None of these circumstances could be considered acceptable. The pressure is very much to achieve a repair and the return to service of the segment as soon as possible. Traditionally this has been achieved by calling on the prearranged services of a suitably equipped repair service. Such services so far have entailed capital intensive solutions comprising purpose built or adapted ships equipped with specialist equipment manned with marine and engineering crews experienced in the work. This all requires a significant initial capital expenditure with substantial annual running costs to maintain each ship and its equipment and crew in the required location and ready for call out. Around 10 years ago, such services were being provided largely by subsidiaries or divisions of the national incumbent telecommunications companies. In the United Kingdom, it was Cable & Wireless Marine and BT Marine. The owners of these businesses, being themselves transoceanic telecommunications cables owners and operators, saw their cable ships as in-
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